Hot melt adhesives and uses thereof

ABSTRACT

The disclosure relates to adhesive compositions comprising a semi-crystalline olefin polymer or copolymer and a functional wax, functional olefin polymer, or mixture thereof. These compositions are useful as, for example, adhesives in disposable articles such as diapers, adult incontinence articles, underpads, personal care garments, and the like.

BACKGROUND OF THE INVENTION

Many conventional hot melt adhesives for elastic applications are basedon styrene block copolymers. These block copolymers provide elasticityand strength through incorporation of an elastomeric mid-block (e.g.,isoprene) and a hard domain end block (e.g., styrene). But in order toapply these adhesives at an appropriate temperature and viscosity, thepolymer content is minimized in favor of higher levels of tackifiers andplasticizers.

Olefin-based chemistry has been explored for use in elastic applicationsbut its use has been limited in view of the lack of balance incohesive/adhesive strength. For example, while an initial creepresistance can sometimes be achieved, that creep resistance isdramatically reduced after thermal aging, resulting in an adhesive thatcan no longer hold strands in place.

There is a need for olefin-based adhesive compositions that possess andmaintain the elastic performance characteristics of a conventionalstyrene block copolymer, even after thermal aging.

SUMMARY OF THE INVENTION

The present disclosure is directed to stretch adhesive compositionscomprising about 25 wt. % to about 75 wt. %, by weight of the stretchadhesive composition, of a semi-crystalline propylene polymer that is ahomo-polymer or co-polymer characterized by a heat of fusion (ΔHm) ofbetween about 4 J/g and about 30 J/g; a storage modulus (E′) at 40° C.and 1 Hz of between about 3.0×10⁸ dyn/cm² and about 1.7×10⁹ dyn/cm²; anda viscosity (η) at 200° C. of between about 2 Pa·s and about 100 Pa·s.The stretch adhesive compositions also comprise between about 1 wt. %and about 10 wt. %, by weight of the stretch adhesive composition, of anadhesion promoter that is a functional wax, functional polyolefin,functional tackifier, functional plasticizer, or a mixture thereof; andbetween about 10 wt. % and about 55 wt. %, by weight of the stretchadhesive composition, of a tackifier. Methods of making and using thesestretch adhesive compositions is also described.

DETAILED DESCRIPTION OF THE INVENTION

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art. In case of conflict, the present document, includingdefinitions, will control. Preferred methods and materials are describedbelow, although methods and materials similar or equivalent to thosedescribed herein can be used in practice or testing of the presentdisclosure. All publications, patent applications, patents and otherreferences mentioned herein are incorporated by reference in theirentirety. The materials, methods, and examples disclosed herein areillustrative only and not intended to be limiting.

As used in the specification and in the claims, the term “comprising”may include the embodiments “consisting of” and “consisting essentiallyof” The terms “comprise(s),” “include(s),” “having,” “has,” “can,”“contain(s),” and variants thereof, as used herein, are intended to beopen-ended transitional phrases, terms, or words that require thepresence of the named ingredients/steps and permit the presence of otheringredients/steps. However, such description should be construed as alsodescribing compositions or processes as “consisting of” and “consistingessentially of” the enumerated ingredients/steps, which allows thepresence of only the named ingredients/steps, along with any impuritiesthat might result therefrom, and excludes other ingredients/steps.

Numerical values in the specification and claims of this application,particularly as they relate to polymers or polymer compositions, reflectaverage values for a composition that may contain individual polymers ofdifferent characteristics. Furthermore, unless indicated to thecontrary, the numerical values should be understood to include numericalvalues which are the same when reduced to the same number of significantfigures and numerical values which differ from the stated value by lessthan the experimental error of conventional measurement technique of thetype described in the present application to determine the value.

All ranges disclosed herein are inclusive of the recited endpoint andindependently combinable (for example, the range of “from 2 to 10” isinclusive of the endpoints, 2 and 10, and all the intermediate values).The endpoints of the ranges and any values disclosed herein are notlimited to the precise range or value; they are sufficiently impreciseto include values approximating these ranges and/or values.

As used herein, approximating language may be applied to modify anyquantitative representation that may vary without resulting in a changein the basic function to which it is related. Accordingly, a valuemodified by a term or terms, such as “about,” may not be limited to theprecise value specified, in some cases. In at least some instances, theapproximating language may correspond to the precision of an instrumentfor measuring the value. The modifier “about” should also be consideredas disclosing the range defined by the absolute values of the twoendpoints. For example, the expression “from about 2 to about 4” alsodiscloses the range “from 2 to 4.” The term “about” may refer to plus orminus 10% of the indicated number. For example, “about 10%” may indicatea range of 9% to 11%, and “about 1” may mean from 0.9-1.1. Othermeanings of “about” may be apparent from the context, such as roundingoff, so, for example “about 1” may also mean from 0.5 to 1.4.

The present disclosure is directed to stretch adhesive compositions.These adhesive compositions comprise about 25 wt. % to about 75 wt. %,by weight of the adhesive composition, of a semi-crystalline propylenepolymer, which can be a homo-polymer or a co-polymer; between about 1wt. % and about 10 wt. %, by weight of the adhesive composition, of anadhesion promoter that is a functional wax, a functional polyolefin,functional tackifier, functional plasticizer, or a mixture thereof; andbetween about 10 wt. % and about 55 wt. %, by weight of the adhesivecomposition, of a tackifier. These adhesive compositions exhibit, forexample, desirable creep performance, even after exposure to long-termaging conditions.

The term “semi-crystalline” used for the propylene polymers refers tothose polymeric materials that contain both crystalline and amorphousregions in the solid state. In the crystalline region, the molecularchains of the polymers are all arranged in ordered three-dimensionalarrays whose structure can be fully characterized by their unit cells,the smallest structural unit used to describe a crystal. The amorphouspolymers, in contrast, do not have ordered three-dimensional structuresin the solid state. Their molecular chains are arranged in a completelyrandom fashion in space. Semi-crystalline polymers can be easilydistinguished from completely amorphous polymers by observing thepresence or absence of a melting point (Tm) and the associated enthalpyor heat of melting (ΔHm) derived from the transformation of thecrystalline state to liquid state upon heating. All semi-crystallinepolymers exhibit a melting point, whereas the melting point is absentfor amorphous polymers. Amorphous polymers undergo a transition from aglassy solid to a rubbery elastic state in a narrow temperature rangearound a glass transition temperature Tg. One should not confuse theglass transition temperature Tg with the melting point Tm. Unlike themelting transition of the crystalline materials, the glass transition ofamorphous polymers do not have an enthalpy change (ΔH) associated withit.

It should be noted that semi-crystalline polymers defined above areoften referred to as crystalline polymers in the trade. Except for thesingle crystals prepared in the laboratories on a small scale, perfectcrystalline polymers are not encountered in the commercial world and allso-called crystalline polymers, strictly speaking, are semi-crystalline.The definition of semi-crystalline polymers set forth herein, therefore,embraces the term “crystalline polymers”.

Since semi-crystalline polymers contain both crystalline and amorphousregions, in addition to melting transition of crystals, they can exhibita glass transition associated with the amorphous region of the material.The glass transition takes place at a temperature below the meltingpoint.

The enthalpy or heat of fusion (ΔHm) can be determined by DifferentialScanning calorimetry (DSC). The technique is well known to those skilledin the art and is well described in the scientific literature.

The semi-crystalline propylene polymers of the disclosure arehomo-polymers or co-polymers. These semi-crystalline propylene polymersare characterized by particular heats of fusion (ΔHm), storage modulus(E′), and viscosity (η), as described herein.

The semi-crystalline propylene polymers are characterized, in part, by aheat of fusion, measured according to ASTM D3418-12, of between about 4J/g and about 30 J/g. For example, the semi-crystalline propylenepolymers of the disclosure are characterized by a heat of fusion ofabout 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,22, 23, 24, 25, 26, 27, 28, 29, or 30 J/g, or any range thereof In someembodiments of the disclosure, the semi-crystalline propylene polymersare characterized by a heat of fusion of between about 4 J/g and about 6J/g. In other embodiments, the semi-crystalline propylene polymers arecharacterized by a heat of fusion of between about 20 J/g and about 24J/g.

The semi-crystalline propylene polymers are also characterized, in part,by a storage modulus (E′), measured at 40° C. and 1 Hz, of between about3.0×10⁸ dyn/cm² and about 1.7×10⁹ dyn/cm². Methods of measuring storagemodulus are known in the art and are described herein. For example, thesemi-crystalline propylene polymers of the disclosure are characterizedby a storage modulus of about 3.0×10⁸, 3.5×10⁸, 4.0×10⁸, 4.5×10⁸,5.0×10⁸, 5.5×10⁸, 6.0×10⁸, 6.5×10⁸, 7.0×10⁸, 7.5×10⁸, 8.0×10⁸, 8.5×10⁸,9.0×10⁸, 9.5×10⁸, 1.0×10⁹, 1.1×10⁹, 1.2×10⁹, 1.3×10⁹, 1.4×10⁹, 1.5×10⁹,1.6×10⁹, or 1.7×10⁹ dyn/cm², or any range thereof. In some preferredembodiments, the semi-crystalline propylene polymers are characterizedby a storage modulus of between about 5.0×10⁸ dyn/cm² to about 1.1×10⁹dyn/cm².

The semi-crystalline propylene polymers are also characterized, in part,by a viscosity, as measured at 200° C., using ASTM D3236, of betweenabout 2 Pa·s and about 100 Pa·s. For example, the semi-crystallinepropylene polymers of the disclosure are characterized by a viscosity ofabout 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 50, 55, 60, 65,70, 75, 80, 85, 90, 95, or 100 Pa·s, or any range thereof. In preferredembodiments, the semi-crystalline propylene polymers are characterizedby a viscosity of between about 2 Pa·s and about 25 Pa·s or about 5 Pa·sand about 25 Pa·s. In preferred embodiments, the semi-crystallinepropylene polymers are characterized by a viscosity of between about 2Pa·s and about 8 Pa·s or about 5 Pa·s and about 8 Pa·s. In otherembodiments, the semi-crystalline propylene polymers are characterizedby a viscosity of between about 20 Pa·s and about 24 Pa·s.

In some embodiments of the disclosure, the semi-crystalline propylenepolymer is a homo-polymer. Preferred semi-crystalline propylenehomo-polymers have medium range tacticity (stereo-regularity) withnarrow and homogenous molecular weight distribution. Such polymers allowfor adequate processability and rigidity, and are useful as componentsin adhesive applications. Polymers having medium range tacticity can bedifferentiated from isotactic and atactic polymers, as described in apresentation titled “The Performance of L-MODU™ for HMA Base PolymerUse” by Idemitsu Kosan Co., Ltd dated November 2014, retrieved fromhttp://www.idemitsu.com/content/100165495.pdf. Isotacticsemi-crystalline propylene homo-polymer have high tacticity and areusually very rigid due to the high levels of crystallinity in thepolymer structure, which make them undesirable for use in adhesivesapplications. Polymers with medium range tacticity are available;however, they typically have broad molecular weight distributions thatcompromise processability when used as a component in adhesives. Onenon-limiting method to control and prepare medium tacticitystereo-regularity and narrow and homogeneous molecular weight polymersis with a metallocene catalyst. Such semi-crystalline propylenehomo-polymers having the characteristics described herein can bepurchased from commercial sources or can be prepared according tomethods described in the art. One preferred semi-crystalline propylenehomo-polymer is L-MODU S-400, available from Idemitsu Kosan Co., Ltd.Other semi-crystalline propylene polymers of interest are S-600 and5-901, also available from Idemitsu. Other semi-crystalline homopolymerswith storage modulus and viscosity within the ranges described hereincan also be used in this invention.

In some embodiments of the disclosure, the semi-crystalline propylenepolymer is a co-polymer. Semi-crystalline propylene co-polymers havingthe required characteristics can be prepared according to methodsdescribed in the art, for example, in U.S. Pat. No. 8,853,329 and U.S.Publication No. 2014/0235127, the entireties of which are incorporatedby reference herein.

The adhesive compositions of the disclosure comprise about 25 wt. % toabout 75 wt. %, by weight of the adhesive composition, of thesemi-crystalline propylene polymer. For example, the adhesivecompositions of the disclosure comprise about 25, 26, 27, 28, 29, 30,31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66,67, 68, 69, 70, 71, 72, 73, 74, or 75 wt. %, or any range thereof, byweight of the adhesive composition, of the semi-crystalline propylenepolymer. Preferred embodiments include about 30 wt. % to about 60 wt. %,by weight of the adhesive composition, of the semi-crystalline propylenepolymer.

The adhesive compositions of the disclosure include between about 1 wt.% and about 10 wt. %, by weight of the adhesive composition, of anadhesion promoter. These adhesion promoters can be, for example, afunctional wax, a functional polyolefin, or a mixture thereof Theseadhesion promoters can alternatively be a functional wax, a functionalpolyolefin, a functional tackifier, a functional plasticizer, afunctional rubber or a mixture thereof The adhesion promoter may bepresent in amounts from about 1 to about 10 wt. %, preferably from 1 wt.% to 5 wt. % or from 1 wt. % to 3 wt. %, based on the total weight ofthe adhesive composition. For example, the adhesive compositions of theinvention can include 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7,7.5, 8, 8.5, 9, 9.5, or 10 wt. %, or any range thereof, of the adhesionpromoter, based on the total weight of the adhesive composition.

The functional groups are present on the backbones of polyolefinpolymers, rubbers, waxes, tackifiers, plasticizers or mixtures thereof.The functional groups may be incorporated by, for example but notlimited to, grafting, copolymerizing or endcapping the functional grouponto the backbone. Suitable functional groups include, for example,carboxylic acid, carboxylic acid esters, anhydride, hydroxyl, thiol,epoxy, amine, urethane, urea, ureido, silane and sulfonate groups.Specific functional groups include silanes, acrylic acid or methacrylicacid, tert-butyl(meth)acrylate, crotonic acid, acrylic acid, acetate,sulfonate, citraconic anhydride, fumaric acid, maleic acid, and itaconicacid, mono- or di-tert-butyl crotonate, mono- or di-tent-butyl fumarateand mono- or di-tert-butyl maleate, maleic anhydride, p-styrenesulfonicacid, 2-(meth)acrylamide-2-methylpropenesulfonic acid,2-sulfonyl(meth)acrylate, vinyloxazolines, glycidyl(meth)acrylate, allylglycidyl ether, and the like. The functional group may be present inamounts from about 0.1 to about 10 wt. %, preferably up to 8 wt. % or upto 5 wt. %, based on the total weight of the functionalized polyolefinpolymers, rubbers, waxes, tackifiers or plasticizers. For example, thefunctional group can include, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8,0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 wt. %, or any range thereof, of thefunctional group, based on the total weight of the functionalizedpolyolefin polymers, rubbers, waxes, tackifiers or plasticizers.

Representative examples of polyolefins include homopolymers andcopolymers of various olefins such as ethylene, propylene, butylene,pentene, hexylene, heptene and octene. Suitable functional groups ontothese polyolefins to form the functional polyolefins of the disclosureinclude, for example, include, for example, carboxylic acid, carboxylicacid esters, anhydride, hydroxyl, thiol, epoxy, amine, urethane, urea,ureido, silane and sulfonate groups. Specific functional groups includesilanes, acrylic acid or methacrylic acid, tert-butyl(meth)acrylate,crotonic acid, acrylic acid, acetate, sulfonate, citraconic anhydride,fumaric acid, maleic acid, and itaconic acid, mono- or di-tert-butylcrotonate, mono- or di-tert-butyl fumarate and mono- or di-tert-butylmaleate, maleic anhydride, p-styrenesulfonic acid,2-(meth)acrylamide-2-methylpropenesulfonic acid,2-sulfonyl(meth)acrylate, vinyloxazolines, glycidyl(meth)acrylate, allylglycidyl ether, and the like.

Representative examples of waxes include homopolymers and copolymers ofvarious olefins such as ethylene, propylene, butylene, pentene,hexylene, heptene and octene. The wax can be of natural or syntheticorigin. Naturally occurring waxes include vegetable waxes, animal waxes,mineral waxes, and petrochemical waxes. Suitable functional groups ontothese waxes to form the functional waxes of the disclosure include, forexample, carboxylic acid, carboxylic acid esters, anhydride, hydroxyl,thiol, epoxy, amine, urethane, urea, ureido, silane, and sulfonategroups. Specific functional groups include silanes, acrylic acid ormethacrylic acid, tert-butyl(meth)acrylate, crotonic acid, acrylic acid,acetate, sulfonate, citraconic anhydride, fumaric acid, maleic acid, anditaconic acid, mono- or di-tert-butyl crotonate, mono- or di-tert-butylfumarate and mono- or di-tert-butyl maleate, maleic anhydride,p-styrenesulfonic acid, 2-(meth)acrylamide-2-methylpropenesulfonic acid,2-sulfonyl(meth)acrylate, vinyloxazolines, glycidyl(meth)acrylate, allylglycidyl ether, and the like.

Fundamentally, the functionalized polyolefin and functionalized wax canboth be homopolymers and copolymers of various olefins such as, but notlimited to, ethylene, propylene, butylene, pentene, hexylene, hepteneand octene containing functional groups described herein. One way todifferentiate a polymer from a wax is by the molecular weight. Polymerstypically have a number average molecular weight of about 5000 g/mol orgreater while waxes have a molecular weight of about 5000 g/mol or less.

Alternatively, functional groups used to prepare the functional waxes ofthe disclosure exclude carboxylic acid and/or anhydride. Thesealternative functional waxes are also known herein as non-carboxylicacid and/or anhydride functional waxes.

In one embodiment, the functionalized wax used in the practice of theinvention is a maleic anhydride grafted on a polypropylene wax. Avariety of maleic anhydride grafted wax suitable for use herein isavailable commercially and/or are obtainable using known procedures. Forexample, maleated polyethylenes are available from Honeywell under thetrade names A-C 575 and A-C 573, and from DuPont as products listed aspart of their Fusabond E series. Maleated polypropylenes are availablefrom Honeywell under the trade names A-C 597A, A-C 597P, A-C 907P, A-C596A, A-C 596P, A-C 950P and A-C 1325P, from DuPont as products listedunder the Fusabond P trade named series, from Eastman under the tradenames G-3015, G-3003, and from Westlake under the trade name EPOLENEE-43. Any known procedures for producing maleated polyolefins fromprecursor compounds can be adapted for use to make starting materialssuitable for use herein. For example, U.S. Pat. No. 7,256,236,incorporated herein by reference, discloses certain preferred methodsfor producing maleated polypropylenes suitable for use herein.

In another embodiment, the functionalized wax is a wax that has beencopolymerized with a functional group. Representative examples ofsuitable copolymerized waxes include terpolymer of ethylene-acrylicester-maleic anhydride and ethylene-acrylic ester-glycidyl methacrylate,available as LOTADER® MΔH and LOTADER® GMA, respectively.

In another embodiment, the functionalized wax is a copolymer ofEthylene-Acrylic acid such as the ones available from Honeywell underthe trade names A-0540, A-0580, A-05120, and A-C 5180.

In a further embodiment, the functionalized wax is an oxidizedpolyethylene homopolymers, including high density oxidized polyethylenehomopolymers. Exemplary oxidized polyethylenes are available fromHoneywell under the trade names A-C 673P, A-C 680, A-C 655, A-C 629, A-C629A, A-C 656, A-C 6702, A-C 307, A-C 307A, A-C 316, A-C316A, A-C 325,A-C 392, A-C 330, A-C 395 and A-C 395A.

In addition to functional polymers or waxes, other common raw materialsused in the making of an adhesive that contain functional groups couldbe used in this invention. Polar tackifiers that contain functionalgroups such as rosin ester for example the partially hydrogenated rosinproduced by Eastman as Staybelite Resin-E and completely hydrogenatedrosin as Foral AX-E. Maleic anhydride modified rosin ester known asLewisol from Eastman is also of interest in this invention. Other polartackifiers such as polyterpene phenolics produced by Arizona as SylvarezTP or AMS phenolic resin produced by Arizona as Sylvarez can also beused as adhesion promoters in the described compositions. Polar liquidplasticizers can also be used as adhesion promoters in the describedcompositions, for example plasticizers derived from rosin ester acidsuch as Abitol E from Eastman or citrate based such as Citroflex 4 fromVertellus Performance Materials.

The adhesive compositions of the disclosure also include between about10 wt. % and about 55 wt. %, by weight of the adhesive composition, of atackifier, i.e., a “tackifiying resin” or “non-functionalizedtackifier.” “Tackifying resins” are understood to mean in particularpolymeric additives that increase their autoadhesion (tack, inherenttack, self-adhesion). For example, the adhesive compositions of thedisclosure include about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39,40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54 or 55 wt. %,or any range thereof, by weight of the adhesive composition, of atackifier. In preferred embodiments, the adhesive compositions of thedisclosure include between about 20 wt. % and about 55 wt. %, by weightof the adhesive composition, of a tackifier.

Typical tackifiers have Ring and Ball softening points, as determined byASTM method E28, of about 70° C. to about 180° C., more preferably about95° C. to about 150° C. Useful tackifying resins may include anycompatible resin or mixtures thereof, such as natural and modifiedrosins including, for example, as gum rosin, wood rosin, tall oil rosin,distilled rosin, hydrogenated rosin, dimerized rosin, resinates, andpolymerized rosin; glycerol and pentaerythritol esters of natural andmodified rosins, including, for example, the glycerol ester of pale,wood rosin, the glycerol ester of hydrogenated rosin, the glycerol esterof polymerized rosin, the pentaerythritol ester of hydrogenated rosin,and the phenolic-modified pentaerythritol ester of rosin; copolymers andterpolymers of natured terpenes, including, for example, styrene/terpeneand alpha methyl styrene/terpene; polyterpene resins having a softeningpoint, as determined by ASTM method E28, from about 70° C. to about 150°C.; phenolic modified terpene resins and hydrogenated derivativesthereof including, for example, the resin product resulting from thecondensation, in an acidic medium, of a bicyclic terpene and a phenol;aliphatic petroleum hydrocarbon resins having a Ball and Ring softeningpoint from about 70° C. to about 135° C.; aromatic petroleum hydrocarbonresins and the hydrogenated derivatives thereof; and alicyclic petroleumhydrocarbon resins and the hydrogenated derivatives thereof. Examples ofhydrogenated tackifiers particularly suitable include Escorez 5400 fromExxon Mobil Chemicals, Arkon PI 00 from Arakawa and Regalite SI 100 fromEastman Chemical, and the like. Also included are the cyclic or acyclicC5 resins and aromatic modified acyclic or cyclic resins. Examples ofcommercially available rosins and rosin derivatives that could be usedto practice the invention include SYLVALITE RE 1 10L, SYLVARES RE 115,and SYLVARES RE 104 available from Arizona Chemical; Dertocal 140 fromDRT; Limed Rosin No. I, GB-120, and Pencel C from Arakawa Chemical.Examples of commercially available phenolic modified terpene resins areSylvares TP 2040 HM and Sylvares TP 300, both available from ArizonaChemical.

Preferred tackifiers are synthetic hydrocarbon resins. Included arealiphatic or cycloaliphatic hydrocarbons, aromatic hydrocarbons,aromatically modified aliphatic or cycloaliphatic hydrocarbons andmixtures thereof.

Non-limiting examples include aliphatic olefin derived resins such asthose available from Goodyear under the Wingtack Extra trade name andthe Escorez 1300 series from Exxon. A common C5 tackifying resin in thisclass is a diene-olefin copolymer of piperylene and 2-methyl-2-butenehaving a softening point of about 95° C. This resin is availablecommercially under the trade name Wingtack 95. Eastotac series fromEastman are also useful in the invention.

Also useful are aromatic hydrocarbon resins that are C9aromatic/aliphatic olefin-derived and available from Sartomer and CrayValley under the trade name Norsolene and from Rutgers series of TKaromatic hydrocarbon resins. Norsolene MI 090 is a low molecular weightthermoplastic hydrocarbon polymer having a Ring and Ball softening pointof 95-105° C. and is commercially available from Cray Valley.

Alpha methyl styrene such as Kristalex 3085 and 3100 from EastmanChemicals, Sylvares S A 100 from Arizona chemicals are also useful astackifiers in the invention. Mixtures of two or more describedtackifying resins may be required for some formulations.

Small quantities of alkyl phenolic tackifiers can be blended withadditional tackifier agents detailed above to improve the hightemperature performance of these adhesives. Alkyl phenolics added inless than 20 wt. % of the total weight of the adhesive are compatibleand in the proper combination increase high temperature adhesiveperformance. Alkyl phenolics are commercially available from ArakawaChemical under the Tamanol trade name and in several product lines fromSchenectady International.

The adhesive compositions of the disclosure may optionally furthercomprise up to 10 wt. %, by weight of the adhesive composition, of asolid plasticizer or a liquid plasticizer. For example, the adhesivecompositions of the disclosure may comprise 0.1, 0.2, 0.3, 0.4, 0.5,0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7,7.5, 8, 8.5, 9, 9.5, or 10 wt. % of a solid plasticizer or a liquidplasticizer. Suitable plasticizers include paraffinic oil, naphthenicoil, aromatic oil, long chain partial ether ester, alkyl monoesters,epoxidized oils, dialkyl diesters, aromatic diesters, alkyl ethermonoester, polybutenes, phthalates, benzoates, adipic esters and thelike. Solid plasticizers, for example those derived from 1,4-cyclohexanedimethanol dibenzoate, available from Eastman Chemical under the name ofBENZOFLEX can also be used in the described compositions. Particularlypreferred plasticizers include mineral oil, aliphatic oils, polybutene,polyisobutylene, olefin oligomers and low molecular weight polymers,vegetable oil, animal oils and derivatives.

The adhesive compositions of the disclosure may optionally furtherinclude up to 10 wt. %, for example, 0.1 wt. % to about 10 wt. %,preferably about 2 wt. % to about 8 wt. %, by weight of the adhesivecomposition, of a non-functionalized wax. For example, the adhesivecompositions of the disclosure can comprise 0.1, 0.2, 0.3, 0.4, 0.5,0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7,7.5, 8, 8.5, 9, 9.5, or 10 wt. %, or any range thereof, by weight of theadhesive composition, of a non-functionalized wax. Representativeexamples of suitable waxes include homopolymers and copolymers ofvarious olefins such as ethylene, propylene, butylene, pentene,hexylene, heptene and octene. The wax can be of natural or syntheticorigin. Naturally occurring waxes that can be added are vegetable waxes,animal waxes, mineral waxes or petrochemical waxes.

Paraffin waxes that can be used in the practice of the invention includePACEMAKER® 30, 32, 35, 37, 40, 42, 45 & 53 available from CitgoPetroleum, Co.; ASTOR OKERIN® 236 available from Honeywell; R-7152Paraffin Wax available from Moore & Munger; R-2540 available from Mooreand Munger; and other paraffinic waxes such as those available fromSasol Wax under the product designations Sasolwax 5603, 6203 and 6805.

The microcrystalline waxes useful here are those having 50 percent byweight or more cyclo or branched alkanes with a length of between 30 and100 carbons. They are generally less crystalline than paraffin andpolyethylene waxes, and have melting points of greater than about 70° C.Examples include VICTORY® Amber Wax, a 70° C. melting point waxavailable from Baker Petrolite Corp.; BARECO® ES-796 Amber Wax, a 70° C.melt point wax available from Bareco; BESQUARE® 175 and 195 Amber Waxesand 80° C. and 90° C. melt point microcrystalline waxes both availablefrom Baker Petrolite Corp.; Indramic® 91, a 90° C. melt point waxavailable from Industrial Raw Materials; and PETROWAX® 9508 Light, a 90°C. melt point wax available from Petrowax. Other examples ofmicrocrystalline waxes are Sasolwax 3971 available from Sasol Wax andMicrowax K4001 available from Alfred Kochem GmBH.

Exemplary high density low molecular weight polyethylene waxes fallingwithin this category include ethylene homopolymers available from BackerPetrolite Corp. as POLYWAX™ 500, POLYWAX™ 1500 and POLYWAX™ 2000.POLYWAX™ 2000 has a molecular weight of approximately 2000, an Mw/Mn ofapproximately 1.0, a density at 16° C. of about 0.97 g/cm³, and amelting point of approximately 126° C. Other examples of polyethylenehomopolymer waxes are AC 9, 9A, 9F, 8, 8A, AC 7, 7A, etc., availablefrom Honeywell.

The adhesive compositions of the disclosure may optionally furthercomprise up to 2.5 wt. %, for example, 0.1 wt. % to 2.5 wt. %,preferably about 0.2 wt. % to about 2.0 wt. %, by weight of the adhesivecomposition, of one or more of an antioxidant, stabilizer, crosslinkingagent, filler, nucleating agent, adhesion promoter, elastomer, colorant,rheology modifier, or a mixture thereof. For example, the adhesivecompositions of the disclosure may include 0.1, 0.2, 0.3, 0.4, 0.5, 0.6,0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1,2.2, 2.3, 2.4, 2.5 wt. %, or any range thereof, by weight of theadhesive composition, of one or more of an antioxidant, stabilizer,crosslinking agent, filler, nucleating agent, elastomer, colorant,rheology modifier, or a mixture thereof.

Applicable stabilizers or antioxidants included herein are highmolecular weight hindered phenols and multifunctional phenols such assulfur and phosphorus-containing phenol. Hindered phenols are well knownto those skilled in the art and may be characterized as phenoliccompounds which also contain sterically bulky radicals in closeproximity to the phenolic hydroxyl group thereof. In particular,tertiary butyl groups generally are substituted onto the benzene ring inat least one of the ortho positions relative to the phenolic hydroxylgroup. The presence of these sterically bulky substituted radicals inthe vicinity of the hydroxyl group serves to retard its stretchingfrequency, and correspondingly, its reactivity; this hindrance thusprovides the phenolic compound with its stabilizing properties.Representative hindered phenols include;1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-benzene;pentacrythrityltetrakis-3(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate;n-octadecyl-3(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate;4,4′-methylenebis(2,6-tert-butyl-phenol);4,4′-thiobis(6-tert-butyl-o-cresol); 2,6-di-tertbutylphenol;6-(4-hydroxyphenoxy)-2,4-bis(n-octyl-thio)-1,3,5 triazine;di-n-octylthio)ethyl 3,5-di-tert-butyl-4-hydroxy-benzoate; and sorbitolhexa[3-(3,5-di-tert-butyl-4-hydroxy-phenyl)-propionate].

Such antioxidants are commercially available from BASF and includeIrganox® 565, 1010, 1076 and 1726 which are hindered phenols. These areprimary antioxidants that act as radical scavengers and may be usedalone or in combination with other antioxidants, such as, phosphiteantioxidants like IRGAFOS® 168 available from BASF. Phosphiteantioxidants are considered secondary antioxidants and are not generallyused alone. These are primarily used as peroxide decomposers. Otheravailable catalysts are CYANOX®LTDP available from Cytec Industries andETHANOX® 330 available from Albemarle Corp. Many such antioxidants areavailable either to be used alone or in combination with other suchantioxidants. These compounds are added to the hot melts in smallamounts, typically less than about 10 wt. %, and have no effect on otherphysical properties. Other compounds that could be added that also donot affect physical properties are pigments, which add color, orfluorescing agents. Additives like these are known to those skilled inthe art.

In general, stabilizers are incorporated in order to protect theadhesive as the end product of the process according to the inventionagainst oxidative or thermal degradation reactions that can occur instorage and/or application. The usable stabilizers preferably includehindered phenols and/or multifunctional phenols, such as for examplesulfur-containing and/or phosphorus-containing phenols. Hindered phenolsare understood to mean compounds, in which at least one stericallyhindered group, such as for example a tert-butyl group, is bonded to thephenol, wherein the sterically hindered groups are located especially inthe ortho and/or para position to the phenolic OH group. Exemplaryhindered phenols that are suitable stabilizers can be selected from thefollowing compounds or from any of their mixtures:1,3,5-trimethyl-2,4,6-tris(3,5-di-tert.-butyl-4-hydroxybenzyl)benzene,pentaerythritol tetrakis-(3,5-di-tert.-butyl-4-hydroxyphenyl)propionate,n-octadecyl-(3,5-di-tert.-butyl-4-hydroxyphenyl)propionate,4,4′-methylene bis(4-methyl-6-tert.-butylphenol),4,4′-thiobis(6-tert.-butyl-o-resol), 2,6-di-tert.-butylphenol,6-(4-hydroxyphenoxy)-2,4-bis(n-octylthio)-1,3,5-triazine,2,4,6-tris(4-hydroxy-3,5-di-tert.-butylphenoxy)-1,3,5-triazine,di-n-octadecyl-3,5-di-tert.-butylbenzyl phosphonate,2-(n-octylthio)ethyl-3,5-di-tert.-butyl-4-hydroxybenzoate and sorbitolhexa-(3,3,5-di-tert.-butyl-4-hydroxyphenyl)propionate.

Further additives can be added, such as for example crosslinking agents,fillers, nucleating agents, elastomers, colorant, rheology modifierswhich are known to the person skilled in the art and can be selectedfrom a great number of commercially available products as a function ofthe desired properties. Additional polymers can be added to modify theadhesive properties. These polymers can be any of the conventional hotmelt polymers as described in: Paul C W (2002) Hot Melt Adhesives in:Chaudhury M and Pocius A V (ed) Surfaces, Chemistry and Applications:Adhesion Science and Engineering, Elsevier Science B. V., TheNetherlands pp 711-757.

The adhesive compositions of the disclosure exhibit a viscosity at 150°C., as measured according to ASTM D3236 of between about 7500 Pa·s andabout 15,000 Pa·s. For example, adhesive compositions of the disclosureexhibit a viscosity at 150° C. of about 7500; 8000; 8500; 9000; 9500;10,000; 10,500; 11,000; 11,500; 12,000; 12,500; 13,000; 13,500; 14,000;14,500; or 15,000 Pa·s, or any range thereof.

The adhesive compositions of the disclosure exhibit a shear modulus(G′), also known as shear storage modulus, at 40° C. and 10 rad/s, asmeasured according to the methods described herein, of between about1.5×10⁶ dyn/cm² to about 2.5×10⁷ dyn/cm². For example, the adhesivecompositions of the disclosure exhibit a sheer modulus at 40° C. ofabout 1.5×10⁶, 2×10⁶, 2.5×10⁶, 3×10⁶, 3.5×10⁶, 4×10⁶, 4.5×10⁶, 5×10⁶,5.5×10⁶, 6×10⁶, 6.5×10⁶, 7×10⁶, 7.5×10⁶, 8×10⁶, 8.5×10⁶, 9×10⁶, 9.5×10⁶,1×10⁷, 1.5×10⁷, 2×10⁷, or 2.5×10⁷ Pa, or any range thereof.

The adhesive compositions of the disclosure exhibit an initial creepresistance that is suitable for use in the described applications. Creepresistance can be measured using the methods described herein. Forexample, adhesive compositions of the disclosure exhibit an initialcreep %, for 25 mg/m/strand, of less than 20%, preferably less than 10%,and even more preferably, less than 7%. For example, adhesivecompositions of the disclosure exhibit an initial creep % of betweenabout 2% and 7%. In certain embodiments, the adhesive compositions ofthe disclosure will exhibit an initial creep % of less than 20%, lessthan 10%, less than 9%, less than 8%, less than 7%, less than 6%, lessthan 5%, less than 4%, less than 3%, or less than 2%.

The adhesive compositions of the disclosure exhibit an aged creep % thatis suitable for use in the described applications. For example, theadhesive compositions of the disclosure exhibit a creep, after 2 weeks(14 days) at 40° C., for 25 mg/m/strand, of less than 40%, preferablyless than 35%. For example, adhesive compositions of the disclosureexhibit a creep, after 2 weeks (14 days) at 40° C. for 25 mg/m/strand,of less than 40%, less than 39%, less than 38%, less than 37%, less than36%, less than 35%, less than 34%, less than 33%, less than 32%, lessthan 31%, less than 30%, less than 29%, less than 28%, less than 27%,less than 26%, less than 25%, less than 24%, less than 23%, less than22%, less than 21%, less than 20%, less than 19%, less than 18%, lessthan 17%, less than 16%, less than 15%, less than 14%, less than 13%,less than 12%, less than 11%, less than 10%, less than 9%, less than 8%,less than 7%, less than 6%, or less than 5%.

In other embodiments, the adhesive compositions of the disclosureexhibit a creep, after 4 weeks (28 days) at 40° C., for 25 mg/m/strand,of less than 40%, preferably less than 35%. For example, adhesivecompositions of the disclosure exhibit a creep, after 4 weeks (28 days)at 40° C. for 25 mg/m/strand, of less than 40%, less than 39%, less than38%, less than 37%, less than 36%, less than 35%, less than 34%, lessthan 33%, less than 32%, less than 31%, less than 30%, less than 29%,less than 28%, less than 27%, less than 26%, less than 25%, less than24%, less than 23%, less than 22%, less than 21%, less than 20%, lessthan 19%, less than 18%, less than 17%, less than 16%, less than 15%,less than 14%, less than 13%, less than 12%, less than 11%, less than10%, less than 9%, less than 8%, less than 7%, less than 6%, or lessthan 5%.

The adhesive compositions of the disclosure exhibit an initial creepresistance that is suitable for use in the described applications. Forexample, adhesive compositions of the disclosure exhibit an initialcreep %, for 35 mg/m/strand, of less than 10%, preferably less than 8%and even more preferably, less than 7%, and most preferably, less than5%. For example, adhesive compositions of the disclosure exhibit aninitial creep %, for 35 mg/m/strand, of between about 1.5% and 3.5%. Incertain embodiments, the adhesive compositions of the disclosure willexhibit an initial creep % of less than 10%, less than 9%, less than 8%,less than 7%, less than 6%, less than 5%, less than 4%, less than 3%, orless than 2%.

The adhesive compositions of the disclosure exhibit an aged creep % thatis suitable for use in the described applications. For example, theadhesive compositions of the disclosure exhibit a creep, after 2 weeks(14 days) at 40° C., for 35 mg/m/strand, of less than 40%, preferablyless than 35%, and more preferably, less than 30%. For example, adhesivecompositions of the disclosure exhibit a creep, after 2 weeks (14 days)at 40° C., for 35 mg/m/strand, of less than 40%, less than 39%, lessthan 38%, less than 37%, less than 36%, less than 35%, less than 34%,less than 33%, less than 32%, less than 31%, less than 30%, less than29%, less than 28%, less than 27%, less than 26%, less than 25%, lessthan 24%, less than 23%, less than 22%, less than 21%, less than 20%,less than 19%, less than 18%, less than 17%, less than 16%, less than15%, less than 14%, less than 13%, less than 12%, less than 11%, lessthan 10%, less than 9%, less than 8%, less than 7%, less than 6%, lessthan 5%, or less than 4%.

In other embodiments, the adhesive compositions of the disclosureexhibit a creep, after 4 weeks (28 days) at 40° C., for 35 mg/m/strand,of less than 40%, preferably less than 35%. For example, adhesivecompositions of the disclosure exhibit a creep, after 4 weeks (28 days)at 40° C., for 35 mg/m/strand, of less than 40%, less than 39%, lessthan 38%, less than 37%, less than 36%, less than 35%, less than 34%,less than 33%, less than 32%, less than 31%, less than 30%, less than29%, less than 28%, less than 27%, less than 26%, less than 25%, lessthan 24%, less than 23%, less than 22%, less than 21%, less than 20%,less than 19%, less than 18%, less than 17%, less than 16%, less than15%, less than 14%, less than 13%, less than 12%, less than 11%, lessthan 10%, less than 9%, less than 8%, less than 7%, less than 6%, orless than 5%_(.)

The adhesive compositions of the present invention are prepared byblending the components in a melt at a temperature above about 180° C.to form a homogeneous blend. Various methods of blending are known inthe art and any method that produces a homogeneous blend. The blend isthen cooled and may be formed into pellets or blocks for storage orshipping. These pre-formed adhesives can then be reheated to apply ontosubstrates.

An elastic attachment article is formed by applying the molten elasticattachment adhesive onto a substrate, at an application temperature ofabout 340° F. (171° C.) or less, preferably less than about 320° F.(160° C.), more preferably less than about 300° F. (149° C.), andplacing another substrate onto the molten adhesive, whereby the adhesiveis sandwiched in between the two substrates. In another embodiment, amultilayer elastic attachment laminant is formed by applying the moltenelastic attachment adhesive onto both sides of a substrate, at anapplication temperature of about 340° F. (171° C.) or less, preferablyless than about 320° F. (160° C.), more preferably less than about 300°F. (149° C.), and placing the substrate in between two additionalsubstrates, whereby the adhesive adheres three substrates together.

The elastic attachment adhesive is typically applied onto a portion ofan elastic strand. Non-limiting examples of elastic strand comprisepolyester, polyurethane, polyether, polyamide, polyacrylate,polyester-b-polyurethane block copolymer, polyether-b-polyurethane blockcopolymer or polyether-b-polyamide block copolymer. Suitable elasticmultifilament strands include LYCRA (Invista, Inc.) CONFI-FIT™(Fulflex).

The adhesive according to the invention may be used to bond or laminatethe same or different substrates materials to one another. In oneembodiment, the elastic strand is attached onto a nonwoven substratewith a basis weight in the range of about 10 to about 35 gsm (g/m²)based on fibers of polyethylene, polypropylene, polyester or cellulose.In another embodiment, the elastic strand is attached to a flexible,elastomeric, sheet-like film. Suitable flexible, elastomer sheet-likefilm are formed from polyethylene, polypropylene, polyester,polyurethane, polyamide, or combinations thereof, including random orgraft copolymers such as styrene block copolymers,polyether-b-polyurethane block copolymer. In another embodiment, theelastic strand is positioned in between one nonwoven substrate and oneelastomeric film with the elastomeric attachment adhesive. Yet inanother embodiment, the elastic strand is positioned in between twononwoven substrates with the elastomeric attachment adhesive bonding thenonwovens and strands in place. The add-on level of the elasticattachment adhesive varies, depending on the type of applicators used,but typically ranges from about 2 to about 50 gsm, preferably from about5 to about 15 gsm for spiral application. The add-on for strand-specificapplications, such as OMEGA™ and SUREWRAP®, varies from 20 to 50milligrams of adhesive/meter/strand. Non-limiting applications includespiral, OMEGA™ (ITW), SUREWRAP® (Nordson), and such techniques are knownto those skilled in the art.

Delivery of consistent and uniform adhesive applied onto the elasticstrand is an important factor to ensure acceptable performance of thelaminant. Adhesives that spray unevenly and inconsistently, e.g.,contain polymers with wide molecular weights or that sprays with angelhair fly-aways, typically have poor creep resistance performance as thelaminant is stretched and aged. Another important factor is adhesion:the adhesive should remain adhered onto the substrates without failureunder strain of deformation. The elastic attachment adhesive of theinstant invention sprays evenly and consistently and remains adheredonto the substrates under strain.

The elastic attachment adhesive is well suited for elastic attachmentarticles. Such articles require low deformation of the adhesive duringexposure to heat and strain over a number of hours. It is preferred thatthe deformation is as small as possible under the heat and strain. Onetypical method of quantifying the resistance to deformation is bymeasuring the creep resistance. Creep resistance is a value calculatedby measuring the initial creep resistance of the article, and thenapplying a strain for a specified temperature and time, and thenre-measuring the resistance. The elastic attachment adhesive of theinstant invention has an initial creep resistance that is less thanabout 20% after extending the laminated adhesive to 250% -300% at 38° C.for four hours. Moreover, the elastic attachment adhesive has a creepresistance that is less than about 20% after four weeks storage at 40°C. followed by extending the adhesive to 250% -300% strain at 38° C. forfour hours.

In order for the elastic attachment adhesive to have an acceptable creepresistance after being aged at 40° C. for up to 4 weeks, the polymerused in the adhesive has to provide enough cohesive strength to keep thelamination held in place during this time. This cohesive strength can bemeasured via rheology by applying some type of deformation on the sampleand recording its response, which is the storage modulus. If thedeformation is applied via shear, the shear storage modulus is measured(G′), while if the deformation is applied via compression or tension,the compression/tension storage modulus is measured (E′). The storagemodulus, either in shear or compression/tension (E′ or G′) is related tothe stiffness and cohesive strength of the material. It has beendiscovered that polymers with storage modulus (E′) between 3.0×10⁸ to1.7×10⁹ dyn/cm², measured at 40° C. and 1 Hz, provide adhesives withexcellent creep after being aged for 2 and 4 weeks at 40° C. The overallcohesive strength of adhesive as measured by the storage modulus onshear mode G′ was also found to be an important property affecting theaged creep. Adhesives with G′, measured at 40° C. and 10 rad/s, rangingfrom 1.5×10⁶ and about 2.5×10⁷ dyn/cm² are useful in the describedadhesives.

The elastic attachment articles are suitable as absorbent articles suchas diapers, diaper pants, baby wipes, training pants, absorbentunderpants, child care pants, swimwear, and other disposable garments;feminine care products including sanitary napkins, wipes, menstrualpads, panty liners, panty shields, tampons, and tampon applicators;adult-care products including wipes, pads, containers, incontinenceproducts, and urinary shields; clothing components; athletic andrecreation products; products for applying hot or cold therapy, medicalgowns (i.e., protective and/or surgical gowns), surgical drapes, caps,gloves, face masks, bandages, wound dressings, wipes, covers,containers, filters, disposable garments and bed pads, medical absorbentgarments, underpads; construction and packaging supplies, industrialpads including meat pads; products for cleaning and disinfecting, wipes,covers, filters, towels, bath tissue, facial tissue, nonwoven rollgoods, home-comfort products including pillows, pads, cushions, masksand body care products such as products used to cleanse or treat theskin, laboratory coats, cover-ails, and the like.

Many modifications and variations of this invention can be made withoutdeparting from its spirit and scope, as will be apparent to thoseskilled in the art. The specific embodiments described herein areoffered by way of example only, and the invention is to be limited onlyby the terms of the appended claims, along with the full scope ofequivalents to which such claims are entitled.

EXAMPLES

Adhesive preparation: Sample adhesive, unless otherwise stated, wasprepared by combining the components together at a temperature where thepolymer was molten, and the mixture became homogeneous.

The heat of fusion (ΔHm) of the polymer was determined by DSC, inaccordance with ASTM D3418-12. The DSC measurements were conducted usinga TA Instruments Q2000 MDSC under the following conditions: a smallsample of around 6-10 mg of the polymer was sealed in an aluminum samplepan, loaded into the instrument at room temperature and heated to 180°C. at a heating rate of 10° C./minute (first heating cycle). The samplewas held for 2 minutes at this temperature to destroy its thermalhistory. After equilibration at this temperature for 2 minutes, thesample was cooled to −40° C. at a cooling rate of 10° C./minute. Thesample was kept at −40° C. for 2 minutes and subsequently heated to 160°C. at 10° C./minute in a second heating phase (second heating cycle).All thermal effects which occurred during the three phases (e.g. glasstransition, peak melting point (Tm), heat of melting (ΔHm) weresubsequently evaluated by software from the experimental data files. Themelting temperatures are the peak melting points from the second heatunless otherwise indicated. For polymers displaying multiple peaks, thehigher melting peak temperature was reported. Areas under the curve wereused to determine the heat of melting (ΔHm). The peak integrationresults were normalized for sample weight and reported in J/g. Meltingpoint was measured with a differential scanning calorimetry apparatus(DSC) in accordance with ASTM 3418-12.

Viscosity was measured with a standard Brookfield viscometer (ThermosellRVT viscosimeter, available from Brookfield Engineering Laboratories,Inc., Stoughton, Mass. USA), at temperatures of 200° C. using spindle 27in accordance with ASTM D3236.

Softening point was measured with a Ring and Ball softening point set upin accordance with ASTM E28.

The storage modulus (E′) of the polymer is measured by DMA Q 800 by TAInstruments. The polymer is tested using film geometry in a torsion modehaving constant 1 Hz frequency and strain within viscoelastic linearregion. The temperature range starts from below 0° C. at ramp rate 5.0°C./min until the polymer melts. The temperature ramp experiment measuresthe viscoelastic properties in dynamic oscillatory mode. The film iscast from the melt and the final solid film has a thickness around 1 mm.Storage modulus at 25° C. and 1 Hz and 40° C. and 1 Hz are reported inTable 1.

The storage modulus (G′) of the adhesive is measured by RheometricScientific RDA III by TA Instruments. The dynamic temperature sweep testis performed by placing an adhesive sample between two parallel plateshaving constant frequency 10 rad/sec and start temperature below 0° C.to until adhesive melts. Throughout the experiment the temperatureincrease by 5° C. in steps.

Elastic sample preparation: Elastic sample laminations were prepared bycontinuous elastic coating application methods known in the art. Theelastic adhesive was applied with add-on levels of 25 or 35 mg/m/strandonto a LYCRA Invista 680 elastic strand with Nordson Surewrap strandapplicator at a 143° C. to 155° C. using a high speed laminator at 1000fpm with 0.1 sec open time. The elastic strand was then laminatedbetween Clopay Breathable PE (143 or 145) substrates and NW PGI nonwoven(15 gsm) substrate with a nip roller and cooled to room temperature.

Elastic Creep Resistance Evaluation: Elastic creep resistance valueswere measured for initial and aged elastic samples. For the agedsamples, the elastic samples were aged at 40° C. for 2 weeks and 4weeks. The creep resistance values are listed as an average of fivesamples.

Creep measurement: The length of an elastic strand adhered in thestretched condition between a nonwoven sheet and a polymeric film wasmeasured and marked (“starting length”). A sample length is stretchedoutside of the marked area. The elastic strands are then cut at themarked area. The amount that the filament retracts is measured followinga 4 hour period at 38° C. The percent creep is then calculated in thefollowing manner:

${\% \mspace{14mu} {creep}} = \frac{\left( {{{starting}\mspace{14mu} {length}} - {{final}\mspace{14mu} {length}}} \right) \times 100\%}{{starting}\mspace{14mu} {length}}$

Acceptable creep resistance of the adhesive is about 35% or less.

Table 1 sets forth certain properties of polymers used in thepreparation of Examples 1 and 2 and Comparative Examples 1, 2, and 3.

“Olefin 1” is a semi-crystalline propylene co-polymer according to thedescription. It can be prepared according to the methods described inU.S. Publication No. 2014/0235127, the entirety of which is incorporatedby reference herein.

L-MODU S-400 is a semi-crystalline propylene homo-polymer according tothe description. It is available from Idemitsu Kosan Co., Ltd.

REXTAC 2814 is an amorphous copolymer (propylene-butene) available fromREXtac LLC.

INFUSE 9817 is an ethylene-octene olefin copolymer, available from Dow.

“Olefin 2” is a semi-crystalline propylene co-polymer. It can beprepared according to the methods described in U.S. Pat. No. 8,853,329,the entirety of which is incorporated by reference herein.

Functionalized polymer is a maleated ethylene copolymer having a meltindex of 660 (g/10 min at 190° C., 2.16 Kg). The functional group,maleic anhydride, is present at about 1 wt %, based on the total weightof the functionalized polymer.

Functionalized wax is an ethylene-acrylic acid copolymer having aviscosity of 575 cP at 140° C. The functional group, acrylic acid, ispresent at about 5 wt % based on the total weight of the functionalizedwax.

TABLE 1 E′ E′ @ 25° C., @ 40° C., Viscosity ΔHm Tm 1 Hz 1 Hz @ 200° C.Polymer (J/g) (° C.) (dyn/cm²) (dyn/cm²) (Pa · s) Olefin 1 27 128 2.7 ×10⁹ 1.9 × 10⁹ 10 Olefin 2 22 139 1.5 × 10⁹  1 × 10⁹ 22.5 L-MODU S- 5.4 78 7.3 × 10⁸ 6.2 × 10⁸ 6.8 400 REXTAC n/a n/a 3.6 × 10⁸ 2.3 × 10⁸ 1.12814 INFUSE 38 124 2.6 × 10⁸ 2.1 × 10⁸ n/a 9817

Examples 1 and 2, and Comparative Examples 1, 2, and 3 were preparedwith the components listed in Table 2. The properties of the adhesivecompositions are listed in Table 3. Henkel DISPOMELT® 897B, arubber-based (styrene-butadiene-styrene and/or styrene-isoprene-styrene)adhesive was used as a control.

TABLE 2 Com- Com- Com- parative parative parative Exam- Exam- Exam-Exam- Exam- Component ple 1 ple 2 ple 1 ple 2 ple 3 Olefin 1 0 0 0 45 0Olefin 2 33 0 0 0 0 L-MODU S-400 0 55 0 0 0 REXTAC 2814 0 0 70 0 0INFUSE 9817 0 0 0 0 15 Functionalized polyolefin 2 0 0 0 0Functionalized wax 0 2 0 0 0 Escorez 5400 51.5 0 0 43.2 0 Eastotac H130R0 33 29.7 0 0 Eastotac H100R 0 0 0 0 60 AC-9 5 5 0 5 0 Epolene C10 0 0 00 14.5 Indopol H300 3 4 0 0 0 Indopol H100 0 0 0 6 0 Calsol 5500 5 0 0 010 Irganox 1010 0.5 1 0.3 0.8 0.5 Total parts 100 100 100 100 100

TABLE 3 Comp. Comp. Comp. Rubber Ex. 1 Ex. 2 Ex. 1 Ex. 2 Ex. 3 (DM897B)Viscosity 150° C. (cP) 13320 7990 3500 6500 8750 5400 Softening point (°C.) 127 104.2 80 133.5 111 92 Adhesive add-on: 25 mg/m/strand InitialCreep Ave. (%) 6.4 3.8 68.0 3.8 8.0 5.0 Aged 2 weeks at 40° C., 30.1 7.8na 25.5 55.0 13.0 ave. (%) Aged 4 weeks at 40° C., 27.1 6.8 na 40.7 51.014.0 ave. (%) Adhesive add-on: 35 mg/m/strand Initial Creep Ave. (%) 2.52.1 68.0 2.6 4 3.0 Aged 2 weeks at 40° C., 27.4 4.6 na 25.7 46 8.0 ave.(%) Aged 4 weeks at 40° C., 32.6 5.0 na 28.3 na 9.0 ave. (%) Tg ° C.12.22 9.37 −1.55 16.75 27.32 28.12 G′ 20° C., 10 rad/s 5.37 × 10⁷ 1.30 ×10⁷ 4.08 × 10⁶ 1.21 × 10⁸ 1.40 × 10⁷ 1.40 × 10⁷ (dyn/cm²) G′ 25° C., 10rad/s 3.53 × 10⁷ 8.14 × 10⁶ 1.71 × 10⁶ 8.54 × 10⁷ 3.21 × 10⁶ 3.21 × 10⁶(dyn/cm²) G′ 40° C., 10 rad/s 1.50 × 10⁷ 2.71 × 10⁶ 6.55 × 10⁵ 3.23 ×10⁷ 3.70 × 10⁵ 3.70 × 10⁵ (dyn/cm²) ΔHm (J/g) 5.7 5.6 na 24 5.0 na Tm (°C.) 134 99 na 126 114 na

Example 1 describes an adhesive where a semi-crystalline polypropylenecopolymer of the disclosure is used for an elastic application. Thesemi-crystalline polypropylene copolymer has the material propertiessuch as storage modulus (E′) at 40° C. and 1 Hz, viscosity, andcrystallinity to provide the necessary stiffness or cohesive strength tomaintain initial and aged creep performance. Example 1 provides anadhesive with balanced material properties, for example storage modulus(G′) at 40° C. and 10 rad/s and processing viscosity.

Example 2 describes an adhesive where a semi-crystalline polypropylenehomopolymer is used for an elastic application. The semi-crystallinepolypropylene homopolymer, L-MODU, has the material properties such asstorage modulus (E′) at 40° C. and 1 Hz, viscosity, and crystallinity toprovide the stiffness or cohesive strength to maintain the initial andaged creep performance. Example 2 provides an adhesive with balancedmaterial properties, for example storage modulus (G′) at 40° C. and 10rad/s and processing viscosity.

Comparative Example 1 describes an adhesive where an amorphouspoly-a-olefin (APAO) is used as the main polymer for an elasticapplication. The lack of crystallinity and the low storage modulus (E′)at 40° C. and 1 Hz for the APAO do not provide the stiffness to maintaineven the initial creep performance.

Comparative Example 2 describes an adhesive where a semi-crystallinepolypropylene copolymer is used for an elastic application. Thesemi-crystalline polypropylene copolymer, olefin 1, has an appropriateviscosity for processing and application of the adhesive, however, eventhough its storage modulus (E′) at 40° C. and 1 Hz and crystallinityprovide stiffness or cohesive strength to maintain the initial creepperformance, the aged creep performance is compromised. The formulationis balanced in such a way to provide an adhesive with the rightprocessing viscosity but the storage modulus (G′) at 40° C. and 10 rad/sappears to be too high, yielding an adhesive too stiff to maintain thecreep performance under aging.

Comparative Example 3 describes an adhesive where an ethylene-octeneolefin copolymer is used for an elastic application. The ethylene-octeneolefin polymer, INFUSE 9817, does not have high enough storage modulus(E′) at 40° C. and 1 Hz to provide the necessary stiffness or cohesivestrength to maintain the aged creep performance which is thencompromised. The formulation is balanced in such a way to provide anadhesive with the right processing viscosity but the storage modulus(G′) at 40° C. and 10 rad/s is too low to maintain the creep performanceafter aging.

Many modifications and variations of this invention can be made withoutdeparting from its spirit and scope, as will be apparent to thoseskilled in the art. The specific embodiments described herein areoffered by way of example only, and the invention is to be limited onlyby the terms of the appended claims, along with the full scope ofequivalents to which such claims are entitled.

What is claimed:
 1. A stretch adhesive composition comprising: about 25wt. % to about 75 wt. %, by weight of the stretch adhesive composition,of a semi-crystalline propylene polymer that is a homo-polymer orco-polymer characterized by a heat of fusion (ΔHm) of between about 4J/g and about 30 J/g; a storage modulus (E′) at 40° C. and 1 Hz ofbetween about 3.0×10⁸ dyn/cm² and about 1.7×10⁹ dyn/cm²; and a viscosity(η) at 200° C. of between about 2 Pa·s and about 100 Pa·s, preferablybetween about 2 Pa·s and about 20 Pa·s; between about 1 wt. % and about10 wt. %, by weight of the stretch adhesive composition, of an adhesionpromoter that is a functional wax, functional polyolefin, functionaltackifier, functional plasticizer, or a mixture thereof; and betweenabout 10 wt. % and about 55 wt. %, preferably about 20 wt. % and about55 wt. %, by weight of the stretch adhesive composition, of a tackifier;wherein the stretch adhesive composition exhibits an initial creepresistance of about 35% or less and an aged creep resistance, afterabout 28 days at about 40° C., of about 35% or less.
 2. The stretchadhesive composition of claim 1, wherein the semi-crystalline propylenepolymer is a homo-polymer.
 3. The stretch adhesive composition of claim1, wherein the semi-crystalline propylene polymer is a co-polymer. 4.The stretch adhesive composition of claim 1, wherein the heat of fusionof the semi-crystalline propylene polymer is between 4 J/g and 6 J/g. 5.The stretch adhesive composition of claim 1, wherein the heat of fusionof the semi-crystalline propylene polymer is between 20 J/g and 24 J/g.6. The stretch adhesive composition of claim 1, wherein the storagemodulus at 40° C. and 1 Hz of the semi-crystalline propylene polymer isbetween about 5.0×10⁸ dyn/cm² and about 1.1×10⁹ dyn/cm².
 7. The stretchadhesive composition of claim 1, wherein the viscosity of thesemi-crystalline propylene polymer @ 200° C. is between 2 Pa·s and 8Pa·s, measured in accordance with ASTM D3236.
 8. The stretch adhesivecomposition of claim 1, wherein the viscosity of the semi-crystallinepropylene polymer @ 200° C. is between 20 Pa·s and 24 Pa·s.
 9. Thestretch adhesive composition of claim 1, comprising between 1 wt. % and5 wt. %, by weight of the adhesive composition, of the adhesionpromoter.
 10. The stretch adhesive composition of claim 1, wherein theadhesion promoter is a functional polyolefin.
 11. The stretch adhesivecomposition of claim 1, wherein the adhesion promoter is a functionalwax.
 12. The stretch adhesive composition of claim 1, further comprisingup to 8 wt. %, by weight of the adhesive composition, of a solidplasticizer or a liquid plasticizer.
 13. The stretch adhesivecomposition of claim 1, further comprising up to 2 wt. % , by weight ofthe adhesive composition, of one or more of an antioxidant, stabilizer,crosslinking agent, filler, nucleating agent, elastomer, colorant,rheology modifier, or a mixture thereof.
 14. The stretch adhesivecomposition of claim 1, further comprising up to 10 wt. % , by weight ofthe adhesive composition, of a non-functionalized wax.
 15. The stretchadhesive composition of claim 1, having a viscosity @ 150° C. of betweenabout 7,500 Pa·s and about 15,000 Pa·s.
 16. The stretch adhesivecomposition of claim 1, characterized by a shear modulus (G′) at 40° C.and 10 rad/s of between about 1.5×10⁶ dyn/cm² and about 2.5×10⁷ dyn/cm².17. An article comprising: a nonwoven substrate; an elastic strand or anelastic film; and an elastic attachment hot melt adhesive comprising thestretch adhesive composition of claim
 1. 18. The article of claim 17that is a diaper, sanitary napkin, pet sheet, hospital gown, or surgicalgarment.
 19. The article of claim 18 comprising a substrate that istissue, cotton, nonwoven fabric, or polyolefin film.
 20. A stretchadhesive composition comprising: about 45 wt. % to about 65 wt. %, byweight of the stretch adhesive composition, of a semi-crystallinepropylene polymer that is a homo-polymer or co-polymer characterized bya heat of fusion (ΔHm) of between about 4 J/g and about 8 J/g; a storagemodulus (E′) at 40° C. and 1 Hz of between about 5.0×10⁸ dyn/cm² andabout 1.1×10⁹ dyn/cm²; and a viscosity (η) at 200° C. of between about 6Pa·s and about 8 Pa·s, measured in accordance with ASTM D3236; betweenabout 1 wt. % and about 10 wt. %, by weight of the stretch adhesivecomposition, of an adhesion promoter that is a functional wax,functional polyolefin, functional tackifier, functional plasticizer, ora mixture thereof; and between about 20 wt. % and about 40 wt. %, byweight of the stretch adhesive composition, of a tackifier; wherein thestretch adhesive composition exhibits an initial creep resistance ofabout 10% or less and an aged creep resistance of about 20% or lessafter about 28 days at about 40° C.